Tooth

A tooth is a hard, mineralized structure in the mouth of most vertebrates, adapted for mechanical processing of food. In humans, teeth are anchored in the jaws and work in coordinated movements during chewing. A mature tooth has a crown above the gum line and one or more roots below. The enamel, the outermost layer of the crown, is the hardest substance in the human body. Beneath the enamel lies dentin, a dense tissue that forms most of the tooth’s bulk and surrounds the central pulp chamber, which contains nerves and blood vessels. The root surface is covered by cementum, and the tooth is held in its socket by the periodontal ligament, which attaches to the surrounding alveolar bone.

Humans typically have four types of teeth: incisors, canines, premolars, and molars, each with specialized shapes and functions for cutting, tearing, and grinding food. A full adult dentition usually consists of 32 teeth, including third molars (wisdom teeth), while a primary (deciduous) set contains 20 teeth that are later replaced.

Tooth development begins before birth. Deciduous teeth emerge in infancy, usually between six months and two years. Permanent teeth develop later and typically erupt from early childhood into adolescence, with some variation among individuals. Tooth loss can result from disease or trauma, and proper care is essential for longevity.

Common dental diseases include caries (tooth decay) and periodontal disease (gum and supporting tissue infection). Prevention and management rely on good oral hygiene, fluoride exposure, limiting fermentable sugars, and regular dental checkups. Treatments range from fillings and crowns to root canal therapy, tooth extraction, and dental implants.